[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Discuss-gnuradio] My First HDTV screenshot from USRP

From: mao mao
Subject: [Discuss-gnuradio] My First HDTV screenshot from USRP
Date: Sun, 2 Apr 2006 21:45:26 -0700 (PDT)

Finally, I got my first HDTV screenshot tonight. It's
from KTVU's "The Loop".

Here's how I did it:
1) Download ATSC stream off USRP with the following
TVRX's rf freq = 725e6
USRP's center freq = 43.75e6
Decim = 8
TVRX's Gain = 88;
USRP's format = 0x300
Mux = 0xf0f0f0f0

See ktvu-complex.png for the FFT pic

2) Upsample 8Ms/s complex data to 40Ms/s complex data:

for every sample in the 8Ms/s data, add 4 zeros, then
followed by a lowpass filter.

3) Downsample 40Ms complex data to 20Ms/s complex
remove every other sample from the 40Ms/s sample data

4) Frequency Translate the center frequency from 0Hz
to 5.75MHz

5) Keep the In-phase part of the 20Ms/s complex data
to get 20Ms/s real data:

See ktvu-real.png for the FFT pic

6) Feed the 20Ms/s real data into Gnuradio 0.9's

Voila! The finally screenshot is here: ktvu-The



Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 

PNG image

PNG image

JPEG image

reply via email to

[Prev in Thread] Current Thread [Next in Thread]